A&A 381, 374-377 (2002)
Linear polarization and composition of VLBI jetsD. Fraix-Burnet
Laboratoire d'Astrophysique de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
(Received 21 November 2000 / Accepted 10 October 2001)
It is shown that linear polarization data can be used to constrain the composition (normal or pair plasma) of pc-scale extragalactic jets. A simple criterion, based on synchrotron and Faraday depolarization properties, is established. It does not depend on the particle density and the length of the emitting region along the line of sight, thus eliminating two physical unknowns.
Key words: galaxies: jet -- galaxies: active -- radiation mechanisms: non-thermal -- radio continuum: galaxies -- polarization -- methods: analytical
© ESO 2002